Dear all, I would like to propose to add* 'flood'* as value to the *key 'hazard'* (to be used in combination with the tag* boundary=hazard*).
Proposal: Hazard <https://wiki.openstreetmap.org/wiki/Key:hazard>=flood would be used in combination with boundary=hazard <https://wiki.openstreetmap.org/wiki/Tag:boundary%3Dhazard> Area hazards are a sub-group of the values of the key:hazard <https://wiki.openstreetmap.org/wiki/Key%3Ahazard> (Proposal <https://wiki.openstreetmap.org/wiki/Proposal:Hazard#Area_hazards>) which apply to areas already tagged as boundary=hazard. For area hazards of natural hazards the tags hazard=avalanche <https://wiki.openstreetmap.org/wiki/Tag%3Ahazard%3Davalanche> and hazard=quicksand <https://wiki.openstreetmap.org/wiki/Tag%3Ahazard%3Dquicksand> already exist. What is currently missing is an option to tag an area hazard as flood hazard. Therefore, the proposed tag hazard=flood is an addition to the existing and approved tag boundary=hazard to allow to tag flood hazard areas. Rationale: The intended use of the tag hazard=flood for area hazards is to map areas where floods <https://en.wikipedia.org/wiki/Flood> (an overflow of water that submerges land that is usually dry) occur. The location and extent of these hazard areas is often well known by local communities with knowledge of past events. Alternatively, NGOs and national agencies can sometimes provide information on hazard areas but capturing and mapping community knowledge of flood occurrences is the preferred use case. The potential use of the data includes supporting exposure analysis of flood hazards for disaster risk reduction programs, raising awareness of flood risks, supporting project plannings of NGOs and local authorities and providing information on routing in case of flooding. A valuable addition to the tag would be to add information on the recurrence of flood extent (return period). The OpenHazardMap <https://wiki.openstreetmap.org/wiki/OpenHazardMap> suggest following classification, which is tailored to capture community knowledge: - < 3 years: any hazard that occurs almost every year (seasonal flood, spring avalanche...). Those are very well-known from communities, as they impact there life and activities every year) - 3 - 50 years: any hazard that occurs more than once in a lifetime - > 50 years: any hazard that happens once (or less in a lifetime) What already exists is the key flood_prone <https://wiki.openstreetmap.org/wiki/Key:flood_prone>=* which is mainly for roads that are known to be flooded frequently. The mapping descriptions include instructions for mapping flood prone waterway crossings, bridges, and highways. However, it is not intended to tag areas, which would be covered by the proposed new tag of hazard=flood for areas tagged as boundary=hazard. The discussed but not approved OpenHazardMap <https://wiki.openstreetmap.org/wiki/OpenHazardMap> project was reviewed as well. However, since this project suggests introducing a row of entirely new tags, it was suggestedto rather add a tag hazard=flood to the already existing and approved key:hazard and boundary=hazard and align with the existing tags of natural hazards (hazard=avalanche; hazard=quicksand). Please let me know your thoughts! Kind regards, Cornelia
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